Due to increasing concern about pest control costs and environmental pollution associated with agricultural sprays, application of such sprays requires precision and care. Considerable research on spray drift has been conducted, but it remains a major problem associated with many agricultural spray applications.
Field tests provide some information on factors influencing spray drift. However, field tests are limited by weather conditions that cannot be controlled and often vary during a test. Due to non-controlled environment, assessing the influence of some variables on spray drift is difficult. Consequently, laboratory tests are used to evaluate drift associated with spray deposits discharged from spray tips at various wind velocities in wind tunnels. However, wind tunnels are generally costly and may expose the tester to the agricultural spray, which can have negative health effects on the tester.
The US EPA will soon implement a new Drift Reduction Technology (DRT) program which would allow farmers and applicators to reduce the size of buffer zones required on some herbicide labels. DRT will need to be certified through the use of spray particle analysis or field trials proving a reduction in fine droplets subject to off-target drift. As a result, more frequent use of wind tunnels may be required for certification.